1. Field of the Invention
This invention relates to nerve tissue stimulation and infusion techniques, and more particularly relates to such techniques for treating depression and manic depression.
2. Description of the Related Art
A persons immediate emotional state is referred to as their affective state. Two normal emotions or affective states are eurphoria and depression. These affective states are experienced transiently by all persons in response life situations. For some individuals however, these normal emotional responses may become sustained for long periods of time. The general affective state may not reflect the momentary expeiences of the individual. Two affective disorders involving the emotions of eurphoria and depression are unipolar or major depression and bipolar depression or manic depression.
Unipolar depression manifests as episodes of dysphoria (unpleasant mood) and anhedonia (inability to experience pleasure) which may last for months. Symptoms may include a loss of energy, changes in weight (most often weight loss but possibly weight gain) insomnia or sometimes oversleeping, restlessness, and inability to concentrate, loss of sex drive, negative thoughts, feelings of worthlessness and suicidal ideation. Unipolar depression is characterized by subtypes. The estimates are that there may be as many as 4 million people in the United States suffering from depression.
Persons with bipolar depression will experience depressive episodes just as those suffering from major depression. These episodes are clinically indistiguishable form those described above. However, they will also experience episodes of mania. Manic episodes are characterized by a prolonged state of euphoria. The person is full of energy with a decreased need for sleep, will have rapid speech and feels grandiose. He or she may have an increased libido and engage in reckless involvements. In severe cases the patient may be delusional and experience hallucinations. Some persons will switch between the two affective states quickly, within a matter of minutes.
Depression can be treated with oral medications. Examples are the monoamine oxidase inhibitors, such as phenelzine, serotonin uptake blockers like trazodone and fluoxetine and trycyclinc compounds like imipramine. Lithium salts are used to terminate manic episodes and prophylactically to prevent reaccurance. Antipsychotic drugs can be used in combination with tricyclics for cases of depression when psychosis is present.
Siuciak (5,599,560) discloses the use of neurotrophins to treat depression. Cosby (4,596,807; 4,698,342) teaches the use of the serotonin precursor l-tryptophan. Owen (4,912,126) discloses the use of 3(H)-indolones. Sgan (4,980,174) describes implanting monoamine producing living cells into the central nervous system to treat depressive patients.
The use of biofeedback to the user of the asymmetry between the brain waves measured at two locations as a means of treating depression is disclosed by Rosenfeld (5,280,793).
Electrical stimulation of the nervous system has been proposed as a therapeutic treatment of depression. Sandyk (5,470,846) disclosed the use of transcranial pulsed magnetic fields to treat depression. Werneke et. al. (5,299,569) discloses electrical stimulation of the vagus nerve and Zabara (5,540,734) teaches stimulation of the trigeminal or glossopharyngeal nerves for psychiatric illness such as depression.